The present invention relates to optical processing apparatus, and in particular, a mechanism that is included in such apparatus for mounting a specimen pattern and providing automatic self-tracking of corresponding regions of the specimen pattern and light pattern or image which is developed from it.
Optical processing apparatus have been used to produce images of specimen subjects for the purpose of examining certain characteristics of them. One such apparatus that employs holographic techniques to develop a three-dimensional image of a subject volume is described in U.S. Pat. No. 4,478,481 of Fusek et al.
In the system of Fusek et al., parallel rays of coherent light strike the subject volume which diffracts them. The diffracted light rays pass through an imaging lens and interfere with a collimated reference beam in a photosensitive recording material to form a hologram of the subject volume. After it is exposed and developed, the recording medium is illuminated by a beam of light that propagates along the path in the conjugate direction of the reference beam to reconstruct from the hologram an image of the subject volume. The light rays reconstructed from the hologram exactly retrace their original paths back through the optical system and provide a three-dimensional real image at the plane of the subject volume. The image produced is then examined by a microscope or other suitable viewing instrument.
Since the reconstructed image appears in the same location where the subject volume was positioned during exposure, it would be advantageous to have a simple mechanism that facilitates not only the exposure of the subject, but also the tracking and inspection of corresponding regions of the reconstructed image and the subject from which the image was developed.